CI: ensure Git-LFS files are checked out in all jobs working with the Git repo
Detailed Description
The igwn/base:conda Docker image does not have git-lfs installed, leading to LALSuite repositories not being checked out correctly by GitLab runners (https://git.ligo.org/computing/helpdesk/-/issues/8089). This should be addressed in docker/base#26 (closed). The manylinux images used to build the wheels are also missing git-lfs, this should be addressed in lalsuite-manylinux#4 (closed).
This MR adds a sanity check to the LALSuite CI: if the repository checkout is needed (i.e. if GIT_STRATEGY is not none), run git lfs ls-files. This will ensure git-lfs is installed in all CI images. The output of git lfs ls-files may be helpful when debugging LFS-related issues.
API Changes
Please tick one of the following options:
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These changes do not modify the API. 
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These changes do modify the API, and are backwards compatible. 
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These changes do modify the API, and are backwards incompatible. 
For examples of changes that do not modify the API and/or are considered backwards (in)compatible, please see the contributing guide.
Justification for Backwards Incompatible Changes
n/a
Review Status
n/a